The present invention relates to a rotary brush suitable for a minute cleaning in a process of the production of articles, for which extremely high surface accuracy and cleanness are required, for example, electronics components, such as silicon wafer, photo masks, magnetic disk substrates, glass substrates for liquid crystal, in particular, to a rotary brush suitable for a brush scrubbing cleaning.
There has been remarkably improved in the accuracy of various articles in electronics industry during recent years, as represented, for example, by the degree of integrity of a silicon wafer or the recording density on a magnetic disk, and Accordingly there have been great demands for the finishing accuracy of the surface of components and cleanness. Especially, chemical contamination or adhered particles on the surface of components could have a great effect on the yield or the reliability of the operation of the products, and therefore the significance of the minute cleaning in a process of production is great.
The wet brush scrubbing method was known as the conventional method for the minute cleaning. In the brush scrubbing method, a rotating brush is forced against an object to be cleaned while scrub-cleaning it with water or other cleaning liquid being supplied, and the method is widely used, since the construction of the apparatus is simple and the cleaning cost is low, and it shows an excellent cleaning power.
There are two types of shape of the brush, a roller type and cup type, used for the brush scrubbing cleaning. The roller type brush makes a line contact whereas the cup type brush makes a plane contact. The cup type brush therefore has advantages of a broader contact area and less cleaning spots as compared with the roller type.
The cup type brush as commonly used has a brush body of a circular disk on which a plurality of synthetic fiber monofilaments is planted or nonwoven fabrics are bonded.
However, the cup brush which employs synthetic fiber monofilaments or nonwoven fabrics would possibly cause other troubles that there were scratches on the surface of an object to be cleaned due to the stiffness of the fiber and the contamination by the fiber coming off, or the like.
With regard to the troubles, there was made a proposal of a cleaning rotary brush using cylindrical projections of a polyvinyl acetal (hereinafter referred to as PVAt) elastomer as a contact portion with an object to be cleaned (Japanese Utility Model Publication No. SHO-64-6953). The PVAt elastomer has excellent water-holding and abrasion resistance properties and shows proper flexibility when water contained Thus, the cleaning rotary brush using PVAt elastomer is suitable for a minute cleaning of electronics components, since it hardly makes scratches on an object to be cleaned and has excellent durability.
In the cup brush, the dirt or particles scrubbed from the surface of an object to be cleaned move together with the spent cleaning liquid over the surface of an object to be cleaned to the outer periphery thereof, and are ultimately drained off to the outside the system.
Although the conventional rotary brush using PVAt porous elastomer described above was constructed taking into consideration the flow of the spent cleaning liquid over the surface of an object to be cleaned, it could not fully meet the increased requirements of the latest minute cleaning. In other words, the spent cleaning liquid containing dirt or particles reside unnecessarily on the surface of an object to be cleaned, and there could be a possibility of the recontamination on the surface of an object to be cleaned of the dirt or particles residing for a longer time, and therefore, it was demanded that the dirt, and the like scrubbed from the surface of an object to be cleaned should be quickly drained off to the outside of the system and the occurrence of such recontamination should be reduced further.
Moreover, in case of the residing particles being hard materials such as grit, when the residing particles are forced against the surface of an object to be cleaned, there could be scratches made by the particles on the surface of the object to be cleaned. Since the PVAt porous elastomer in contact with the surface of the object to be cleaned is flexible in the conventional rotary brush as described above, such undesirable matter could be overcome to some extent, and however, the latest increased requirements of the minute cleaning could not be met satisfactorily, and in this respect, it was desired that the residing particles, and the like could be quickly drained off to the outside of the system. In view of the circumstances discussed above, the present invention has been made, and the object is to provide a cleaning rotary brush which can drain off the particles scrubbed from an object to be cleaned quickly to the outside of the system and has an excellent cleaning efficiency.
In order to achieve the objects mentioned above, in the first embodiment of the present invention, a cleaning rotary brush is provided with a hard base, when mounted to a rotary shaft, having a rotating working surface opposite a portion to be cleaned, and a plurality of cleaning members disposed on and projecting from the working surface, the tops of said cleaning members being in contact with said portion to be cleaned while rotating in substantially the same plane, characterized in that said cleaning members made of a polyvinyl acetal porous elastomer and comprising a plurality of ridged projections positioned continually on a plurality of phantom setting lines extending from inner reference points on the side of the center of rotation of the working surface to outer reference points on the side of the outer periphery of the working surface, and the length in a longitudinal direction of said ridged projections along said phantom setting lines being made longer than the length in a widthwise direction of the ridged projections.
In the first embodiment, the inner reference point may be disposed further inside the inner circle of the two concentric circles which trisect the distance between the intersections of a line passing through the center of rotation with the innermost and outermost edges of the sheet, and the outer reference point may be disposed further outside the outer circle of the two circles.
Incidentally, the inner reference point may be disposed adjacent to the innermost edge of the sheet, and the outer reference point may be disposed adjacent to the outermost edge of the sheet.
In the second embodiment of the present invention, a cleaning rotary brush is provided with a sheet member mounted on and rotating in unity with a rotating working surface opposite a portion to be cleaned and cleaning members disposed on and projecting from the sheet member, the tops of said cleaning members rotating in substantially the same plane while being in contact with the portion to be cleaned, characterized in that said cleaning members being made of a polyvinyl acetal porous elastomer and comprising a plurality of ridged projections positioned continually on a plurality of phantom setting lines extending from inner reference points on the side of the center of rotation of the sheet member to outer reference points on the side of the outer periphery of the sheet member, and the length in a longitudinal direction of said ridged projections along said phantom setting lines being formed longer than the length in a widthwise direction of the ridged projections.
In the second embodiment, the inner reference point may be disposed further inside the inner circle of the two concentric circles which trisect the distance between the intersections of a line passing through the center of rotation with the innermost and outermost edges of the sheet member, and the outer reference point may be disposed further outside the outer circle of the two circles.
Furthermore, the inner reference point may be disposed adjacent to the innermost edge of the sheet member, and the outer reference point may be disposed adjacent to the outermost edge of the sheet member.
Incidentally, the sheet member and ridged projections may also be made in unity of a polyvinyl acetal porous elastomer.
Besides, in the first or second embodiment, the ridged projections may be formed integrally and continually for each of the phantom setting lines.
Incidentally, the length in a longitudinal direction of the ridged projections may be formed more than or equal to twice the length in a widthwise direction.
Furthermore, the length in a widthwise direction of the ridged projections may be formed varying with the position on the phantom setting line.
The third embodiment of the present invention is characterized in that the phantom setting lines are generally a straight line in the cleaning rotary brush of the first or second embodiment.
The fourth embodiment of the present invention is characterized in that the phantom setting lines are at a slant to a line passing through the center of rotation in the cleaning rotary brush of the third embodiment.
In the fourth embodiment, the crossing angle between the phantom setting line and the line passing through the center of rotation and a midpoint that bisects the distance between the inner and outer reference points of the phantom setting line may be limited to a range of 0xc2x0 to 4xc2x0.
Besides, the phantom setting lines may be all set at a slant backward in a direction of the rotation of the base or sheet member.
In the fifth embodiment of the present invention, the cleaning rotary brush of the first or second embodiment is characterized in that the phantom setting lines are curvilinear.
In the sixth embodiment of the present invention, the cleaning rotary brush of the embodiment is characterized in that the phantom setting lines are a curve protruding in one direction, and a tangent to the phantom setting line at a midpoint which bisects the length along the phantom setting line between the inner and outer reference points is at a slant with respect to a line passing through the center of rotation and midpoint.
In the sixth embodiment, the crossing angle between the tangent and the line passing through the midpoint and center of rotation may be limited to a range of more than 0xc2x0 to 45xc2x0.
Incidentally, the tangents to the respective curved lines at the midpoints may be all set at a slant backwards in a direction of rotation of the base or sheet member.
Moreover, all the curved lines may be made to protrude forwards in a direction of the rotation of the base or the sheet member.
In the seventh embodiment of the present invention, the cleaning rotary brush of the fifth or sixth embodiment is characterized in that the phantom setting lines are a curved line protruding in one direction, and the crossing angle between a line passing through the center of rotation and an arbitrary point on the phantom setting line and a tangent to the curved line at the arbitrary point approaches 90xc2x0 as the arbitrary point goes away from the center of rotation.
In the seventh embodiment, the crossing angle may be changed in a range of 0xc2x0 to 45xc2x0.
When a portion to be cleaned is cleaned using the cleaning rotary brush of each of the embodiments discussed above, the ridged projections rotating at a high speed by the rotating shaft are forced against the portion to be cleaned at the same time water or other cleaning liquid is supplied over the portion to be cleaned. By doing this, the portion to be cleaned is scrub-cleaned effectively by means of the ridged projections made of PVAt porous elastomer. Then, the dirt or particles scrubbed from the portion to be cleaned move together with the spent cleaning liquid to the outer periphery side and are finally drained off to outside of the system.
At this time, as the ridged projections continually extend from the inner reference points on the side of the center of rotation of the working surface or sheet member to the outer reference points on the side of the outer periphery, the spent cleaning liquid containing the dirt or particles scrubbed from the portion to be cleaned receives a centrifugal force and is adequately guided to the outer reference points. Thus, the spent cleaning liquid is rapidly drained off to the outside of the system and the residence time of the dirt or particles are remarkably reduced.